mqueue.c

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    1 /*
    2  * POSIX message queues filesystem for Linux.
    3  *
    4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
    5  *                          Michal Wronski          (michal.wronski@gmail.com)
    6  *
    7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
    8  * Lockless receive & send, fd based notify:
    9  *                          Manfred Spraul          (manfred@colorfullife.com)
   10  *
   11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
   12  *
   13  * This file is released under the GPL.
   14  */
   15 
   16 #include <linux/capability.h>
   17 #include <linux/init.h>
   18 #include <linux/pagemap.h>
   19 #include <linux/file.h>
   20 #include <linux/mount.h>
   21 #include <linux/namei.h>
   22 #include <linux/sysctl.h>
   23 #include <linux/poll.h>
   24 #include <linux/mqueue.h>
   25 #include <linux/msg.h>
   26 #include <linux/skbuff.h>
   27 #include <linux/vmalloc.h>
   28 #include <linux/netlink.h>
   29 #include <linux/syscalls.h>
   30 #include <linux/audit.h>
   31 #include <linux/signal.h>
   32 #include <linux/mutex.h>
   33 #include <linux/nsproxy.h>
   34 #include <linux/pid.h>
   35 #include <linux/ipc_namespace.h>
   36 #include <linux/user_namespace.h>
   37 #include <linux/slab.h>
   38 
   39 #include <net/sock.h>
   40 #include "util.h"
   41 
   42 #define MQUEUE_MAGIC    0x19800202
   43 #define DIRENT_SIZE     20
   44 #define FILENT_SIZE     80
   45 
   46 #define SEND            0
   47 #define RECV            1
   48 
   49 #define STATE_NONE      0
   50 #define STATE_PENDING   1
   51 #define STATE_READY     2
   52 
   53 struct posix_msg_tree_node {
   54         struct rb_node          rb_node;
   55         struct list_head        msg_list;
   56         int                     priority;
   57 };
   58 
   59 struct ext_wait_queue {         /* queue of sleeping tasks */
   60         struct task_struct *task;
   61         struct list_head list;
   62         struct msg_msg *msg;    /* ptr of loaded message */
   63         int state;              /* one of STATE_* values */
   64 };
   65 
   66 struct mqueue_inode_info {
   67         spinlock_t lock;
   68         struct inode vfs_inode;
   69         wait_queue_head_t wait_q;
   70 
   71         struct rb_root msg_tree;
   72         struct posix_msg_tree_node *node_cache;
   73         struct mq_attr attr;
   74 
   75         struct sigevent notify;
   76         struct pid* notify_owner;
   77         struct user_namespace *notify_user_ns;
   78         struct user_struct *user;       /* user who created, for accounting */
   79         struct sock *notify_sock;
   80         struct sk_buff *notify_cookie;
   81 
   82         /* for tasks waiting for free space and messages, respectively */
   83         struct ext_wait_queue e_wait_q[2];
   84 
   85         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
   86 };
   87 
   88 static const struct inode_operations mqueue_dir_inode_operations;
   89 static const struct file_operations mqueue_file_operations;
   90 static const struct super_operations mqueue_super_ops;
   91 static void remove_notification(struct mqueue_inode_info *info);
   92 
   93 static struct kmem_cache *mqueue_inode_cachep;
   94 
   95 static struct ctl_table_header * mq_sysctl_table;
   96 
   97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
   98 {
   99         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  100 }
  101 
  102 /*
  103  * This routine should be called with the mq_lock held.
  104  */
  105 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  106 {
  107         return get_ipc_ns(inode->i_sb->s_fs_info);
  108 }
  109 
  110 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
  111 {
  112         struct ipc_namespace *ns;
  113 
  114         spin_lock(&mq_lock);
  115         ns = __get_ns_from_inode(inode);
  116         spin_unlock(&mq_lock);
  117         return ns;
  118 }
  119 
  120 /* Auxiliary functions to manipulate messages' list */
  121 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
  122 {
  123         struct rb_node **p, *parent = NULL;
  124         struct posix_msg_tree_node *leaf;
  125 
  126         p = &info->msg_tree.rb_node;
  127         while (*p) {
  128                 parent = *p;
  129                 leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
  130 
  131                 if (likely(leaf->priority == msg->m_type))
  132                         goto insert_msg;
  133                 else if (msg->m_type < leaf->priority)
  134                         p = &(*p)->rb_left;
  135                 else
  136                         p = &(*p)->rb_right;
  137         }
  138         if (info->node_cache) {
  139                 leaf = info->node_cache;
  140                 info->node_cache = NULL;
  141         } else {
  142                 leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
  143                 if (!leaf)
  144                         return -ENOMEM;
  145                 INIT_LIST_HEAD(&leaf->msg_list);
  146                 info->qsize += sizeof(*leaf);
  147         }
  148         leaf->priority = msg->m_type;
  149         rb_link_node(&leaf->rb_node, parent, p);
  150         rb_insert_color(&leaf->rb_node, &info->msg_tree);
  151 insert_msg:
  152         info->attr.mq_curmsgs++;
  153         info->qsize += msg->m_ts;
  154         list_add_tail(&msg->m_list, &leaf->msg_list);
  155         return 0;
  156 }
  157 
  158 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
  159 {
  160         struct rb_node **p, *parent = NULL;
  161         struct posix_msg_tree_node *leaf;
  162         struct msg_msg *msg;
  163 
  164 try_again:
  165         p = &info->msg_tree.rb_node;
  166         while (*p) {
  167                 parent = *p;
  168                 /*
  169                  * During insert, low priorities go to the left and high to the
  170                  * right.  On receive, we want the highest priorities first, so
  171                  * walk all the way to the right.
  172                  */
  173                 p = &(*p)->rb_right;
  174         }
  175         if (!parent) {
  176                 if (info->attr.mq_curmsgs) {
  177                         pr_warn_once("Inconsistency in POSIX message queue, "
  178                                      "no tree element, but supposedly messages "
  179                                      "should exist!\n");
  180                         info->attr.mq_curmsgs = 0;
  181                 }
  182                 return NULL;
  183         }
  184         leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
  185         if (unlikely(list_empty(&leaf->msg_list))) {
  186                 pr_warn_once("Inconsistency in POSIX message queue, "
  187                              "empty leaf node but we haven't implemented "
  188                              "lazy leaf delete!\n");
  189                 rb_erase(&leaf->rb_node, &info->msg_tree);
  190                 if (info->node_cache) {
  191                         info->qsize -= sizeof(*leaf);
  192                         kfree(leaf);
  193                 } else {
  194                         info->node_cache = leaf;
  195                 }
  196                 goto try_again;
  197         } else {
  198                 msg = list_first_entry(&leaf->msg_list,
  199                                        struct msg_msg, m_list);
  200                 list_del(&msg->m_list);
  201                 if (list_empty(&leaf->msg_list)) {
  202                         rb_erase(&leaf->rb_node, &info->msg_tree);
  203                         if (info->node_cache) {
  204                                 info->qsize -= sizeof(*leaf);
  205                                 kfree(leaf);
  206                         } else {
  207                                 info->node_cache = leaf;
  208                         }
  209                 }
  210         }
  211         info->attr.mq_curmsgs--;
  212         info->qsize -= msg->m_ts;
  213         return msg;
  214 }
  215 
  216 static struct inode *mqueue_get_inode(struct super_block *sb,
  217                 struct ipc_namespace *ipc_ns, umode_t mode,
  218                 struct mq_attr *attr)
  219 {
  220         struct user_struct *u = current_user();
  221         struct inode *inode;
  222         int ret = -ENOMEM;
  223 
  224         inode = new_inode(sb);
  225         if (!inode)
  226                 goto err;
  227 
  228         inode->i_ino = get_next_ino();
  229         inode->i_mode = mode;
  230         inode->i_uid = current_fsuid();
  231         inode->i_gid = current_fsgid();
  232         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
  233 
  234         if (S_ISREG(mode)) {
  235                 struct mqueue_inode_info *info;
  236                 unsigned long mq_bytes, mq_treesize;
  237 
  238                 inode->i_fop = &mqueue_file_operations;
  239                 inode->i_size = FILENT_SIZE;
  240                 /* mqueue specific info */
  241                 info = MQUEUE_I(inode);
  242                 spin_lock_init(&info->lock);
  243                 init_waitqueue_head(&info->wait_q);
  244                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
  245                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
  246                 info->notify_owner = NULL;
  247                 info->notify_user_ns = NULL;
  248                 info->qsize = 0;
  249                 info->user = NULL;      /* set when all is ok */
  250                 info->msg_tree = RB_ROOT;
  251                 info->node_cache = NULL;
  252                 memset(&info->attr, 0, sizeof(info->attr));
  253                 info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
  254                                            ipc_ns->mq_msg_default);
  255                 info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
  256                                             ipc_ns->mq_msgsize_default);
  257                 if (attr) {
  258                         info->attr.mq_maxmsg = attr->mq_maxmsg;
  259                         info->attr.mq_msgsize = attr->mq_msgsize;
  260                 }
  261                 /*
  262                  * We used to allocate a static array of pointers and account
  263                  * the size of that array as well as one msg_msg struct per
  264                  * possible message into the queue size. That's no longer
  265                  * accurate as the queue is now an rbtree and will grow and
  266                  * shrink depending on usage patterns.  We can, however, still
  267                  * account one msg_msg struct per message, but the nodes are
  268                  * allocated depending on priority usage, and most programs
  269                  * only use one, or a handful, of priorities.  However, since
  270                  * this is pinned memory, we need to assume worst case, so
  271                  * that means the min(mq_maxmsg, max_priorities) * struct
  272                  * posix_msg_tree_node.
  273                  */
  274                 mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
  275                         min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
  276                         sizeof(struct posix_msg_tree_node);
  277 
  278                 mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
  279                                           info->attr.mq_msgsize);
  280 
  281                 spin_lock(&mq_lock);
  282                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
  283                     u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
  284                         spin_unlock(&mq_lock);
  285                         /* mqueue_evict_inode() releases info->messages */
  286                         ret = -EMFILE;
  287                         goto out_inode;
  288                 }
  289                 u->mq_bytes += mq_bytes;
  290                 spin_unlock(&mq_lock);
  291 
  292                 /* all is ok */
  293                 info->user = get_uid(u);
  294         } else if (S_ISDIR(mode)) {
  295                 inc_nlink(inode);
  296                 /* Some things misbehave if size == 0 on a directory */
  297                 inode->i_size = 2 * DIRENT_SIZE;
  298                 inode->i_op = &mqueue_dir_inode_operations;
  299                 inode->i_fop = &simple_dir_operations;
  300         }
  301 
  302         return inode;
  303 out_inode:
  304         iput(inode);
  305 err:
  306         return ERR_PTR(ret);
  307 }
  308 
  309 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
  310 {
  311         struct inode *inode;
  312         struct ipc_namespace *ns = data;
  313 
  314         sb->s_blocksize = PAGE_CACHE_SIZE;
  315         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  316         sb->s_magic = MQUEUE_MAGIC;
  317         sb->s_op = &mqueue_super_ops;
  318 
  319         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
  320         if (IS_ERR(inode))
  321                 return PTR_ERR(inode);
  322 
  323         sb->s_root = d_make_root(inode);
  324         if (!sb->s_root)
  325                 return -ENOMEM;
  326         return 0;
  327 }
  328 
  329 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
  330                          int flags, const char *dev_name,
  331                          void *data)
  332 {
  333         if (!(flags & MS_KERNMOUNT))
  334                 data = current->nsproxy->ipc_ns;
  335         return mount_ns(fs_type, flags, data, mqueue_fill_super);
  336 }
  337 
  338 static void init_once(void *foo)
  339 {
  340         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
  341 
  342         inode_init_once(&p->vfs_inode);
  343 }
  344 
  345 static struct inode *mqueue_alloc_inode(struct super_block *sb)
  346 {
  347         struct mqueue_inode_info *ei;
  348 
  349         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
  350         if (!ei)
  351                 return NULL;
  352         return &ei->vfs_inode;
  353 }
  354 
  355 static void mqueue_i_callback(struct rcu_head *head)
  356 {
  357         struct inode *inode = container_of(head, struct inode, i_rcu);
  358         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
  359 }
  360 
  361 static void mqueue_destroy_inode(struct inode *inode)
  362 {
  363         call_rcu(&inode->i_rcu, mqueue_i_callback);
  364 }
  365 
  366 static void mqueue_evict_inode(struct inode *inode)
  367 {
  368         struct mqueue_inode_info *info;
  369         struct user_struct *user;
  370         unsigned long mq_bytes, mq_treesize;
  371         struct ipc_namespace *ipc_ns;
  372         struct msg_msg *msg;
  373 
  374         clear_inode(inode);
  375 
  376         if (S_ISDIR(inode->i_mode))
  377                 return;
  378 
  379         ipc_ns = get_ns_from_inode(inode);
  380         info = MQUEUE_I(inode);
  381         spin_lock(&info->lock);
  382         while ((msg = msg_get(info)) != NULL)
  383                 free_msg(msg);
  384         kfree(info->node_cache);
  385         spin_unlock(&info->lock);
  386 
  387         /* Total amount of bytes accounted for the mqueue */
  388         mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
  389                 min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
  390                 sizeof(struct posix_msg_tree_node);
  391 
  392         mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
  393                                   info->attr.mq_msgsize);
  394 
  395         user = info->user;
  396         if (user) {
  397                 spin_lock(&mq_lock);
  398                 user->mq_bytes -= mq_bytes;
  399                 /*
  400                  * get_ns_from_inode() ensures that the
  401                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
  402                  * to which we now hold a reference, or it is NULL.
  403                  * We can't put it here under mq_lock, though.
  404                  */
  405                 if (ipc_ns)
  406                         ipc_ns->mq_queues_count--;
  407                 spin_unlock(&mq_lock);
  408                 free_uid(user);
  409         }
  410         if (ipc_ns)
  411                 put_ipc_ns(ipc_ns);
  412 }
  413 
  414 static int mqueue_create(struct inode *dir, struct dentry *dentry,
  415                                 umode_t mode, bool excl)
  416 {
  417         struct inode *inode;
  418         struct mq_attr *attr = dentry->d_fsdata;
  419         int error;
  420         struct ipc_namespace *ipc_ns;
  421 
  422         spin_lock(&mq_lock);
  423         ipc_ns = __get_ns_from_inode(dir);
  424         if (!ipc_ns) {
  425                 error = -EACCES;
  426                 goto out_unlock;
  427         }
  428         if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
  429             (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
  430              !capable(CAP_SYS_RESOURCE))) {
  431                 error = -ENOSPC;
  432                 goto out_unlock;
  433         }
  434         ipc_ns->mq_queues_count++;
  435         spin_unlock(&mq_lock);
  436 
  437         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
  438         if (IS_ERR(inode)) {
  439                 error = PTR_ERR(inode);
  440                 spin_lock(&mq_lock);
  441                 ipc_ns->mq_queues_count--;
  442                 goto out_unlock;
  443         }
  444 
  445         put_ipc_ns(ipc_ns);
  446         dir->i_size += DIRENT_SIZE;
  447         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
  448 
  449         d_instantiate(dentry, inode);
  450         dget(dentry);
  451         return 0;
  452 out_unlock:
  453         spin_unlock(&mq_lock);
  454         if (ipc_ns)
  455                 put_ipc_ns(ipc_ns);
  456         return error;
  457 }
  458 
  459 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
  460 {
  461         struct inode *inode = dentry->d_inode;
  462 
  463         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
  464         dir->i_size -= DIRENT_SIZE;
  465         drop_nlink(inode);
  466         dput(dentry);
  467         return 0;
  468 }
  469 
  470 /*
  471 *       This is routine for system read from queue file.
  472 *       To avoid mess with doing here some sort of mq_receive we allow
  473 *       to read only queue size & notification info (the only values
  474 *       that are interesting from user point of view and aren't accessible
  475 *       through std routines)
  476 */
  477 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
  478                                 size_t count, loff_t *off)
  479 {
  480         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
  481         char buffer[FILENT_SIZE];
  482         ssize_t ret;
  483 
  484         spin_lock(&info->lock);
  485         snprintf(buffer, sizeof(buffer),
  486                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
  487                         info->qsize,
  488                         info->notify_owner ? info->notify.sigev_notify : 0,
  489                         (info->notify_owner &&
  490                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
  491                                 info->notify.sigev_signo : 0,
  492                         pid_vnr(info->notify_owner));
  493         spin_unlock(&info->lock);
  494         buffer[sizeof(buffer)-1] = '\0';
  495 
  496         ret = simple_read_from_buffer(u_data, count, off, buffer,
  497                                 strlen(buffer));
  498         if (ret <= 0)
  499                 return ret;
  500 
  501         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
  502         return ret;
  503 }
  504 
  505 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
  506 {
  507         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
  508 
  509         spin_lock(&info->lock);
  510         if (task_tgid(current) == info->notify_owner)
  511                 remove_notification(info);
  512 
  513         spin_unlock(&info->lock);
  514         return 0;
  515 }
  516 
  517 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
  518 {
  519         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
  520         int retval = 0;
  521 
  522         poll_wait(filp, &info->wait_q, poll_tab);
  523 
  524         spin_lock(&info->lock);
  525         if (info->attr.mq_curmsgs)
  526                 retval = POLLIN | POLLRDNORM;
  527 
  528         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
  529                 retval |= POLLOUT | POLLWRNORM;
  530         spin_unlock(&info->lock);
  531 
  532         return retval;
  533 }
  534 
  535 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
  536 static void wq_add(struct mqueue_inode_info *info, int sr,
  537                         struct ext_wait_queue *ewp)
  538 {
  539         struct ext_wait_queue *walk;
  540 
  541         ewp->task = current;
  542 
  543         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
  544                 if (walk->task->static_prio <= current->static_prio) {
  545                         list_add_tail(&ewp->list, &walk->list);
  546                         return;
  547                 }
  548         }
  549         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
  550 }
  551 
  552 /*
  553  * Puts current task to sleep. Caller must hold queue lock. After return
  554  * lock isn't held.
  555  * sr: SEND or RECV
  556  */
  557 static int wq_sleep(struct mqueue_inode_info *info, int sr,
  558                     ktime_t *timeout, struct ext_wait_queue *ewp)
  559 {
  560         int retval;
  561         signed long time;
  562 
  563         wq_add(info, sr, ewp);
  564 
  565         for (;;) {
  566                 set_current_state(TASK_INTERRUPTIBLE);
  567 
  568                 spin_unlock(&info->lock);
  569                 time = schedule_hrtimeout_range_clock(timeout, 0,
  570                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
  571 
  572                 while (ewp->state == STATE_PENDING)
  573                         cpu_relax();
  574 
  575                 if (ewp->state == STATE_READY) {
  576                         retval = 0;
  577                         goto out;
  578                 }
  579                 spin_lock(&info->lock);
  580                 if (ewp->state == STATE_READY) {
  581                         retval = 0;
  582                         goto out_unlock;
  583                 }
  584                 if (signal_pending(current)) {
  585                         retval = -ERESTARTSYS;
  586                         break;
  587                 }
  588                 if (time == 0) {
  589                         retval = -ETIMEDOUT;
  590                         break;
  591                 }
  592         }
  593         list_del(&ewp->list);
  594 out_unlock:
  595         spin_unlock(&info->lock);
  596 out:
  597         return retval;
  598 }
  599 
  600 /*
  601  * Returns waiting task that should be serviced first or NULL if none exists
  602  */
  603 static struct ext_wait_queue *wq_get_first_waiter(
  604                 struct mqueue_inode_info *info, int sr)
  605 {
  606         struct list_head *ptr;
  607 
  608         ptr = info->e_wait_q[sr].list.prev;
  609         if (ptr == &info->e_wait_q[sr].list)
  610                 return NULL;
  611         return list_entry(ptr, struct ext_wait_queue, list);
  612 }
  613 
  614 
  615 static inline void set_cookie(struct sk_buff *skb, char code)
  616 {
  617         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
  618 }
  619 
  620 /*
  621  * The next function is only to split too long sys_mq_timedsend
  622  */
  623 static void __do_notify(struct mqueue_inode_info *info)
  624 {
  625         /* notification
  626          * invoked when there is registered process and there isn't process
  627          * waiting synchronously for message AND state of queue changed from
  628          * empty to not empty. Here we are sure that no one is waiting
  629          * synchronously. */
  630         if (info->notify_owner &&
  631             info->attr.mq_curmsgs == 1) {
  632                 struct siginfo sig_i;
  633                 switch (info->notify.sigev_notify) {
  634                 case SIGEV_NONE:
  635                         break;
  636                 case SIGEV_SIGNAL:
  637                         /* sends signal */
  638 
  639                         sig_i.si_signo = info->notify.sigev_signo;
  640                         sig_i.si_errno = 0;
  641                         sig_i.si_code = SI_MESGQ;
  642                         sig_i.si_value = info->notify.sigev_value;
  643                         /* map current pid/uid into info->owner's namespaces */
  644                         rcu_read_lock();
  645                         sig_i.si_pid = task_tgid_nr_ns(current,
  646                                                 ns_of_pid(info->notify_owner));
  647                         sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
  648                         rcu_read_unlock();
  649 
  650                         kill_pid_info(info->notify.sigev_signo,
  651                                       &sig_i, info->notify_owner);
  652                         break;
  653                 case SIGEV_THREAD:
  654                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
  655                         netlink_sendskb(info->notify_sock, info->notify_cookie);
  656                         break;
  657                 }
  658                 /* after notification unregisters process */
  659                 put_pid(info->notify_owner);
  660                 put_user_ns(info->notify_user_ns);
  661                 info->notify_owner = NULL;
  662                 info->notify_user_ns = NULL;
  663         }
  664         wake_up(&info->wait_q);
  665 }
  666 
  667 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
  668                            ktime_t *expires, struct timespec *ts)
  669 {
  670         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
  671                 return -EFAULT;
  672         if (!timespec_valid(ts))
  673                 return -EINVAL;
  674 
  675         *expires = timespec_to_ktime(*ts);
  676         return 0;
  677 }
  678 
  679 static void remove_notification(struct mqueue_inode_info *info)
  680 {
  681         if (info->notify_owner != NULL &&
  682             info->notify.sigev_notify == SIGEV_THREAD) {
  683                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
  684                 netlink_sendskb(info->notify_sock, info->notify_cookie);
  685         }
  686         put_pid(info->notify_owner);
  687         put_user_ns(info->notify_user_ns);
  688         info->notify_owner = NULL;
  689         info->notify_user_ns = NULL;
  690 }
  691 
  692 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
  693 {
  694         int mq_treesize;
  695         unsigned long total_size;
  696 
  697         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
  698                 return -EINVAL;
  699         if (capable(CAP_SYS_RESOURCE)) {
  700                 if (attr->mq_maxmsg > HARD_MSGMAX ||
  701                     attr->mq_msgsize > HARD_MSGSIZEMAX)
  702                         return -EINVAL;
  703         } else {
  704                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
  705                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
  706                         return -EINVAL;
  707         }
  708         /* check for overflow */
  709         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
  710                 return -EOVERFLOW;
  711         mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
  712                 min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
  713                 sizeof(struct posix_msg_tree_node);
  714         total_size = attr->mq_maxmsg * attr->mq_msgsize;
  715         if (total_size + mq_treesize < total_size)
  716                 return -EOVERFLOW;
  717         return 0;
  718 }
  719 
  720 /*
  721  * Invoked when creating a new queue via sys_mq_open
  722  */
  723 static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
  724                         struct path *path, int oflag, umode_t mode,
  725                         struct mq_attr *attr)
  726 {
  727         const struct cred *cred = current_cred();
  728         int ret;
  729 
  730         if (attr) {
  731                 ret = mq_attr_ok(ipc_ns, attr);
  732                 if (ret)
  733                         return ERR_PTR(ret);
  734                 /* store for use during create */
  735                 path->dentry->d_fsdata = attr;
  736         } else {
  737                 struct mq_attr def_attr;
  738 
  739                 def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
  740                                          ipc_ns->mq_msg_default);
  741                 def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
  742                                           ipc_ns->mq_msgsize_default);
  743                 ret = mq_attr_ok(ipc_ns, &def_attr);
  744                 if (ret)
  745                         return ERR_PTR(ret);
  746         }
  747 
  748         mode &= ~current_umask();
  749         ret = vfs_create(dir, path->dentry, mode, true);
  750         path->dentry->d_fsdata = NULL;
  751         if (ret)
  752                 return ERR_PTR(ret);
  753         return dentry_open(path, oflag, cred);
  754 }
  755 
  756 /* Opens existing queue */
  757 static struct file *do_open(struct path *path, int oflag)
  758 {
  759         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
  760                                                   MAY_READ | MAY_WRITE };
  761         int acc;
  762         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
  763                 return ERR_PTR(-EINVAL);
  764         acc = oflag2acc[oflag & O_ACCMODE];
  765         if (inode_permission(path->dentry->d_inode, acc))
  766                 return ERR_PTR(-EACCES);
  767         return dentry_open(path, oflag, current_cred());
  768 }
  769 
  770 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
  771                 struct mq_attr __user *, u_attr)
  772 {
  773         struct path path;
  774         struct file *filp;
  775         struct filename *name;
  776         struct mq_attr attr;
  777         int fd, error;
  778         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
  779         struct vfsmount *mnt = ipc_ns->mq_mnt;
  780         struct dentry *root = mnt->mnt_root;
  781         int ro;
  782 
  783         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
  784                 return -EFAULT;
  785 
  786         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
  787 
  788         if (IS_ERR(name = getname(u_name)))
  789                 return PTR_ERR(name);
  790 
  791         fd = get_unused_fd_flags(O_CLOEXEC);
  792         if (fd < 0)
  793                 goto out_putname;
  794 
  795         ro = mnt_want_write(mnt);       /* we'll drop it in any case */
  796         error = 0;
  797         mutex_lock(&root->d_inode->i_mutex);
  798         path.dentry = lookup_one_len(name->name, root, strlen(name->name));
  799         if (IS_ERR(path.dentry)) {
  800                 error = PTR_ERR(path.dentry);
  801                 goto out_putfd;
  802         }
  803         path.mnt = mntget(mnt);
  804 
  805         if (oflag & O_CREAT) {
  806                 if (path.dentry->d_inode) {     /* entry already exists */
  807                         audit_inode(name, path.dentry, 0);
  808                         if (oflag & O_EXCL) {
  809                                 error = -EEXIST;
  810                                 goto out;
  811                         }
  812                         filp = do_open(&path, oflag);
  813                 } else {
  814                         if (ro) {
  815                                 error = ro;
  816                                 goto out;
  817                         }
  818                         filp = do_create(ipc_ns, root->d_inode,
  819                                                 &path, oflag, mode,
  820                                                 u_attr ? &attr : NULL);
  821                 }
  822         } else {
  823                 if (!path.dentry->d_inode) {
  824                         error = -ENOENT;
  825                         goto out;
  826                 }
  827                 audit_inode(name, path.dentry, 0);
  828                 filp = do_open(&path, oflag);
  829         }
  830 
  831         if (!IS_ERR(filp))
  832                 fd_install(fd, filp);
  833         else
  834                 error = PTR_ERR(filp);
  835 out:
  836         path_put(&path);
  837 out_putfd:
  838         if (error) {
  839                 put_unused_fd(fd);
  840                 fd = error;
  841         }
  842         mutex_unlock(&root->d_inode->i_mutex);
  843         mnt_drop_write(mnt);
  844 out_putname:
  845         putname(name);
  846         return fd;
  847 }
  848 
  849 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
  850 {
  851         int err;
  852         struct filename *name;
  853         struct dentry *dentry;
  854         struct inode *inode = NULL;
  855         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
  856         struct vfsmount *mnt = ipc_ns->mq_mnt;
  857 
  858         name = getname(u_name);
  859         if (IS_ERR(name))
  860                 return PTR_ERR(name);
  861 
  862         err = mnt_want_write(mnt);
  863         if (err)
  864                 goto out_name;
  865         mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
  866         dentry = lookup_one_len(name->name, mnt->mnt_root,
  867                                 strlen(name->name));
  868         if (IS_ERR(dentry)) {
  869                 err = PTR_ERR(dentry);
  870                 goto out_unlock;
  871         }
  872 
  873         inode = dentry->d_inode;
  874         if (!inode) {
  875                 err = -ENOENT;
  876         } else {
  877                 ihold(inode);
  878                 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
  879         }
  880         dput(dentry);
  881 
  882 out_unlock:
  883         mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
  884         if (inode)
  885                 iput(inode);
  886         mnt_drop_write(mnt);
  887 out_name:
  888         putname(name);
  889 
  890         return err;
  891 }
  892 
  893 /* Pipelined send and receive functions.
  894  *
  895  * If a receiver finds no waiting message, then it registers itself in the
  896  * list of waiting receivers. A sender checks that list before adding the new
  897  * message into the message array. If there is a waiting receiver, then it
  898  * bypasses the message array and directly hands the message over to the
  899  * receiver.
  900  * The receiver accepts the message and returns without grabbing the queue
  901  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
  902  * are necessary. The same algorithm is used for sysv semaphores, see
  903  * ipc/sem.c for more details.
  904  *
  905  * The same algorithm is used for senders.
  906  */
  907 
  908 /* pipelined_send() - send a message directly to the task waiting in
  909  * sys_mq_timedreceive() (without inserting message into a queue).
  910  */
  911 static inline void pipelined_send(struct mqueue_inode_info *info,
  912                                   struct msg_msg *message,
  913                                   struct ext_wait_queue *receiver)
  914 {
  915         receiver->msg = message;
  916         list_del(&receiver->list);
  917         receiver->state = STATE_PENDING;
  918         wake_up_process(receiver->task);
  919         smp_wmb();
  920         receiver->state = STATE_READY;
  921 }
  922 
  923 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
  924  * gets its message and put to the queue (we have one free place for sure). */
  925 static inline void pipelined_receive(struct mqueue_inode_info *info)
  926 {
  927         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
  928 
  929         if (!sender) {
  930                 /* for poll */
  931                 wake_up_interruptible(&info->wait_q);
  932                 return;
  933         }
  934         if (msg_insert(sender->msg, info))
  935                 return;
  936         list_del(&sender->list);
  937         sender->state = STATE_PENDING;
  938         wake_up_process(sender->task);
  939         smp_wmb();
  940         sender->state = STATE_READY;
  941 }
  942 
  943 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
  944                 size_t, msg_len, unsigned int, msg_prio,
  945                 const struct timespec __user *, u_abs_timeout)
  946 {
  947         struct fd f;
  948         struct inode *inode;
  949         struct ext_wait_queue wait;
  950         struct ext_wait_queue *receiver;
  951         struct msg_msg *msg_ptr;
  952         struct mqueue_inode_info *info;
  953         ktime_t expires, *timeout = NULL;
  954         struct timespec ts;
  955         struct posix_msg_tree_node *new_leaf = NULL;
  956         int ret = 0;
  957 
  958         if (u_abs_timeout) {
  959                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
  960                 if (res)
  961                         return res;
  962                 timeout = &expires;
  963         }
  964 
  965         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
  966                 return -EINVAL;
  967 
  968         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
  969 
  970         f = fdget(mqdes);
  971         if (unlikely(!f.file)) {
  972                 ret = -EBADF;
  973                 goto out;
  974         }
  975 
  976         inode = f.file->f_path.dentry->d_inode;
  977         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
  978                 ret = -EBADF;
  979                 goto out_fput;
  980         }
  981         info = MQUEUE_I(inode);
  982         audit_inode(NULL, f.file->f_path.dentry, 0);
  983 
  984         if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
  985                 ret = -EBADF;
  986                 goto out_fput;
  987         }
  988 
  989         if (unlikely(msg_len > info->attr.mq_msgsize)) {
  990                 ret = -EMSGSIZE;
  991                 goto out_fput;
  992         }
  993 
  994         /* First try to allocate memory, before doing anything with
  995          * existing queues. */
  996         msg_ptr = load_msg(u_msg_ptr, msg_len);
  997         if (IS_ERR(msg_ptr)) {
  998                 ret = PTR_ERR(msg_ptr);
  999                 goto out_fput;
 1000         }
 1001         msg_ptr->m_ts = msg_len;
 1002         msg_ptr->m_type = msg_prio;
 1003 
 1004         /*
 1005          * msg_insert really wants us to have a valid, spare node struct so
 1006          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
 1007          * fall back to that if necessary.
 1008          */
 1009         if (!info->node_cache)
 1010                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
 1011 
 1012         spin_lock(&info->lock);
 1013 
 1014         if (!info->node_cache && new_leaf) {
 1015                 /* Save our speculative allocation into the cache */
 1016                 INIT_LIST_HEAD(&new_leaf->msg_list);
 1017                 info->node_cache = new_leaf;
 1018                 info->qsize += sizeof(*new_leaf);
 1019                 new_leaf = NULL;
 1020         } else {
 1021                 kfree(new_leaf);
 1022         }
 1023 
 1024         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 1025                 if (f.file->f_flags & O_NONBLOCK) {
 1026                         ret = -EAGAIN;
 1027                 } else {
 1028                         wait.task = current;
 1029                         wait.msg = (void *) msg_ptr;
 1030                         wait.state = STATE_NONE;
 1031                         ret = wq_sleep(info, SEND, timeout, &wait);
 1032                         /*
 1033                          * wq_sleep must be called with info->lock held, and
 1034                          * returns with the lock released
 1035                          */
 1036                         goto out_free;
 1037                 }
 1038         } else {
 1039                 receiver = wq_get_first_waiter(info, RECV);
 1040                 if (receiver) {
 1041                         pipelined_send(info, msg_ptr, receiver);
 1042                 } else {
 1043                         /* adds message to the queue */
 1044                         ret = msg_insert(msg_ptr, info);
 1045                         if (ret)
 1046                                 goto out_unlock;
 1047                         __do_notify(info);
 1048                 }
 1049                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 1050                                 CURRENT_TIME;
 1051         }
 1052 out_unlock:
 1053         spin_unlock(&info->lock);
 1054 out_free:
 1055         if (ret)
 1056                 free_msg(msg_ptr);
 1057 out_fput:
 1058         fdput(f);
 1059 out:
 1060         return ret;
 1061 }
 1062 
 1063 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 1064                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 1065                 const struct timespec __user *, u_abs_timeout)
 1066 {
 1067         ssize_t ret;
 1068         struct msg_msg *msg_ptr;
 1069         struct fd f;
 1070         struct inode *inode;
 1071         struct mqueue_inode_info *info;
 1072         struct ext_wait_queue wait;
 1073         ktime_t expires, *timeout = NULL;
 1074         struct timespec ts;
 1075         struct posix_msg_tree_node *new_leaf = NULL;
 1076 
 1077         if (u_abs_timeout) {
 1078                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 1079                 if (res)
 1080                         return res;
 1081                 timeout = &expires;
 1082         }
 1083 
 1084         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 1085 
 1086         f = fdget(mqdes);
 1087         if (unlikely(!f.file)) {
 1088                 ret = -EBADF;
 1089                 goto out;
 1090         }
 1091 
 1092         inode = f.file->f_path.dentry->d_inode;
 1093         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
 1094                 ret = -EBADF;
 1095                 goto out_fput;
 1096         }
 1097         info = MQUEUE_I(inode);
 1098         audit_inode(NULL, f.file->f_path.dentry, 0);
 1099 
 1100         if (unlikely(!(f.file->f_mode & FMODE_READ))) {
 1101                 ret = -EBADF;
 1102                 goto out_fput;
 1103         }
 1104 
 1105         /* checks if buffer is big enough */
 1106         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 1107                 ret = -EMSGSIZE;
 1108                 goto out_fput;
 1109         }
 1110 
 1111         /*
 1112          * msg_insert really wants us to have a valid, spare node struct so
 1113          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
 1114          * fall back to that if necessary.
 1115          */
 1116         if (!info->node_cache)
 1117                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
 1118 
 1119         spin_lock(&info->lock);
 1120 
 1121         if (!info->node_cache && new_leaf) {
 1122                 /* Save our speculative allocation into the cache */
 1123                 INIT_LIST_HEAD(&new_leaf->msg_list);
 1124                 info->node_cache = new_leaf;
 1125                 info->qsize += sizeof(*new_leaf);
 1126         } else {
 1127                 kfree(new_leaf);
 1128         }
 1129 
 1130         if (info->attr.mq_curmsgs == 0) {
 1131                 if (f.file->f_flags & O_NONBLOCK) {
 1132                         spin_unlock(&info->lock);
 1133                         ret = -EAGAIN;
 1134                 } else {
 1135                         wait.task = current;
 1136                         wait.state = STATE_NONE;
 1137                         ret = wq_sleep(info, RECV, timeout, &wait);
 1138                         msg_ptr = wait.msg;
 1139                 }
 1140         } else {
 1141                 msg_ptr = msg_get(info);
 1142 
 1143                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 1144                                 CURRENT_TIME;
 1145 
 1146                 /* There is now free space in queue. */
 1147                 pipelined_receive(info);
 1148                 spin_unlock(&info->lock);
 1149                 ret = 0;
 1150         }
 1151         if (ret == 0) {
 1152                 ret = msg_ptr->m_ts;
 1153 
 1154                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 1155                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 1156                         ret = -EFAULT;
 1157                 }
 1158                 free_msg(msg_ptr);
 1159         }
 1160 out_fput:
 1161         fdput(f);
 1162 out:
 1163         return ret;
 1164 }
 1165 
 1166 /*
 1167  * Notes: the case when user wants us to deregister (with NULL as pointer)
 1168  * and he isn't currently owner of notification, will be silently discarded.
 1169  * It isn't explicitly defined in the POSIX.
 1170  */
 1171 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
 1172                 const struct sigevent __user *, u_notification)
 1173 {
 1174         int ret;
 1175         struct fd f;
 1176         struct sock *sock;
 1177         struct inode *inode;
 1178         struct sigevent notification;
 1179         struct mqueue_inode_info *info;
 1180         struct sk_buff *nc;
 1181 
 1182         if (u_notification) {
 1183                 if (copy_from_user(&notification, u_notification,
 1184                                         sizeof(struct sigevent)))
 1185                         return -EFAULT;
 1186         }
 1187 
 1188         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
 1189 
 1190         nc = NULL;
 1191         sock = NULL;
 1192         if (u_notification != NULL) {
 1193                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
 1194                              notification.sigev_notify != SIGEV_SIGNAL &&
 1195                              notification.sigev_notify != SIGEV_THREAD))
 1196                         return -EINVAL;
 1197                 if (notification.sigev_notify == SIGEV_SIGNAL &&
 1198                         !valid_signal(notification.sigev_signo)) {
 1199                         return -EINVAL;
 1200                 }
 1201                 if (notification.sigev_notify == SIGEV_THREAD) {
 1202                         long timeo;
 1203 
 1204                         /* create the notify skb */
 1205                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
 1206                         if (!nc) {
 1207                                 ret = -ENOMEM;
 1208                                 goto out;
 1209                         }
 1210                         if (copy_from_user(nc->data,
 1211                                         notification.sigev_value.sival_ptr,
 1212                                         NOTIFY_COOKIE_LEN)) {
 1213                                 ret = -EFAULT;
 1214                                 goto out;
 1215                         }
 1216 
 1217                         /* TODO: add a header? */
 1218                         skb_put(nc, NOTIFY_COOKIE_LEN);
 1219                         /* and attach it to the socket */
 1220 retry:
 1221                         f = fdget(notification.sigev_signo);
 1222                         if (!f.file) {
 1223                                 ret = -EBADF;
 1224                                 goto out;
 1225                         }
 1226                         sock = netlink_getsockbyfilp(f.file);
 1227                         fdput(f);
 1228                         if (IS_ERR(sock)) {
 1229                                 ret = PTR_ERR(sock);
 1230                                 sock = NULL;
 1231                                 goto out;
 1232                         }
 1233 
 1234                         timeo = MAX_SCHEDULE_TIMEOUT;
 1235                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
 1236                         if (ret == 1)
 1237                                 goto retry;
 1238                         if (ret) {
 1239                                 sock = NULL;
 1240                                 nc = NULL;
 1241                                 goto out;
 1242                         }
 1243                 }
 1244         }
 1245 
 1246         f = fdget(mqdes);
 1247         if (!f.file) {
 1248                 ret = -EBADF;
 1249                 goto out;
 1250         }
 1251 
 1252         inode = f.file->f_path.dentry->d_inode;
 1253         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
 1254                 ret = -EBADF;
 1255                 goto out_fput;
 1256         }
 1257         info = MQUEUE_I(inode);
 1258 
 1259         ret = 0;
 1260         spin_lock(&info->lock);
 1261         if (u_notification == NULL) {
 1262                 if (info->notify_owner == task_tgid(current)) {
 1263                         remove_notification(info);
 1264                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
 1265                 }
 1266         } else if (info->notify_owner != NULL) {
 1267                 ret = -EBUSY;
 1268         } else {
 1269                 switch (notification.sigev_notify) {
 1270                 case SIGEV_NONE:
 1271                         info->notify.sigev_notify = SIGEV_NONE;
 1272                         break;
 1273                 case SIGEV_THREAD:
 1274                         info->notify_sock = sock;
 1275                         info->notify_cookie = nc;
 1276                         sock = NULL;
 1277                         nc = NULL;
 1278                         info->notify.sigev_notify = SIGEV_THREAD;
 1279                         break;
 1280                 case SIGEV_SIGNAL:
 1281                         info->notify.sigev_signo = notification.sigev_signo;
 1282                         info->notify.sigev_value = notification.sigev_value;
 1283                         info->notify.sigev_notify = SIGEV_SIGNAL;
 1284                         break;
 1285                 }
 1286 
 1287                 info->notify_owner = get_pid(task_tgid(current));
 1288                 info->notify_user_ns = get_user_ns(current_user_ns());
 1289                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
 1290         }
 1291         spin_unlock(&info->lock);
 1292 out_fput:
 1293         fdput(f);
 1294 out:
 1295         if (sock) {
 1296                 netlink_detachskb(sock, nc);
 1297         } else if (nc) {
 1298                 dev_kfree_skb(nc);
 1299         }
 1300         return ret;
 1301 }
 1302 
 1303 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
 1304                 const struct mq_attr __user *, u_mqstat,
 1305                 struct mq_attr __user *, u_omqstat)
 1306 {
 1307         int ret;
 1308         struct mq_attr mqstat, omqstat;
 1309         struct fd f;
 1310         struct inode *inode;
 1311         struct mqueue_inode_info *info;
 1312 
 1313         if (u_mqstat != NULL) {
 1314                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
 1315                         return -EFAULT;
 1316                 if (mqstat.mq_flags & (~O_NONBLOCK))
 1317                         return -EINVAL;
 1318         }
 1319 
 1320         f = fdget(mqdes);
 1321         if (!f.file) {
 1322                 ret = -EBADF;
 1323                 goto out;
 1324         }
 1325 
 1326         inode = f.file->f_path.dentry->d_inode;
 1327         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
 1328                 ret = -EBADF;
 1329                 goto out_fput;
 1330         }
 1331         info = MQUEUE_I(inode);
 1332 
 1333         spin_lock(&info->lock);
 1334 
 1335         omqstat = info->attr;
 1336         omqstat.mq_flags = f.file->f_flags & O_NONBLOCK;
 1337         if (u_mqstat) {
 1338                 audit_mq_getsetattr(mqdes, &mqstat);
 1339                 spin_lock(&f.file->f_lock);
 1340                 if (mqstat.mq_flags & O_NONBLOCK)
 1341                         f.file->f_flags |= O_NONBLOCK;
 1342                 else
 1343                         f.file->f_flags &= ~O_NONBLOCK;
 1344                 spin_unlock(&f.file->f_lock);
 1345 
 1346                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
 1347         }
 1348 
 1349         spin_unlock(&info->lock);
 1350 
 1351         ret = 0;
 1352         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
 1353                                                 sizeof(struct mq_attr)))
 1354                 ret = -EFAULT;
 1355 
 1356 out_fput:
 1357         fdput(f);
 1358 out:
 1359         return ret;
 1360 }
 1361 
 1362 static const struct inode_operations mqueue_dir_inode_operations = {
 1363         .lookup = simple_lookup,
 1364         .create = mqueue_create,
 1365         .unlink = mqueue_unlink,
 1366 };
 1367 
 1368 static const struct file_operations mqueue_file_operations = {
 1369         .flush = mqueue_flush_file,
 1370         .poll = mqueue_poll_file,
 1371         .read = mqueue_read_file,
 1372         .llseek = default_llseek,
 1373 };
 1374 
 1375 static const struct super_operations mqueue_super_ops = {
 1376         .alloc_inode = mqueue_alloc_inode,
 1377         .destroy_inode = mqueue_destroy_inode,
 1378         .evict_inode = mqueue_evict_inode,
 1379         .statfs = simple_statfs,
 1380 };
 1381 
 1382 static struct file_system_type mqueue_fs_type = {
 1383         .name = "mqueue",
 1384         .mount = mqueue_mount,
 1385         .kill_sb = kill_litter_super,
 1386 };
 1387 
 1388 int mq_init_ns(struct ipc_namespace *ns)
 1389 {
 1390         ns->mq_queues_count  = 0;
 1391         ns->mq_queues_max    = DFLT_QUEUESMAX;
 1392         ns->mq_msg_max       = DFLT_MSGMAX;
 1393         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
 1394         ns->mq_msg_default   = DFLT_MSG;
 1395         ns->mq_msgsize_default  = DFLT_MSGSIZE;
 1396 
 1397         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
 1398         if (IS_ERR(ns->mq_mnt)) {
 1399                 int err = PTR_ERR(ns->mq_mnt);
 1400                 ns->mq_mnt = NULL;
 1401                 return err;
 1402         }
 1403         return 0;
 1404 }
 1405 
 1406 void mq_clear_sbinfo(struct ipc_namespace *ns)
 1407 {
 1408         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
 1409 }
 1410 
 1411 void mq_put_mnt(struct ipc_namespace *ns)
 1412 {
 1413         kern_unmount(ns->mq_mnt);
 1414 }
 1415 
 1416 static int __init init_mqueue_fs(void)
 1417 {
 1418         int error;
 1419 
 1420         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
 1421                                 sizeof(struct mqueue_inode_info), 0,
 1422                                 SLAB_HWCACHE_ALIGN, init_once);
 1423         if (mqueue_inode_cachep == NULL)
 1424                 return -ENOMEM;
 1425 
 1426         /* ignore failures - they are not fatal */
 1427         mq_sysctl_table = mq_register_sysctl_table();
 1428 
 1429         error = register_filesystem(&mqueue_fs_type);
 1430         if (error)
 1431                 goto out_sysctl;
 1432 
 1433         spin_lock_init(&mq_lock);
 1434 
 1435         error = mq_init_ns(&init_ipc_ns);
 1436         if (error)
 1437                 goto out_filesystem;
 1438 
 1439         return 0;
 1440 
 1441 out_filesystem:
 1442         unregister_filesystem(&mqueue_fs_type);
 1443 out_sysctl:
 1444         if (mq_sysctl_table)
 1445                 unregister_sysctl_table(mq_sysctl_table);
 1446         kmem_cache_destroy(mqueue_inode_cachep);
 1447         return error;
 1448 }
 1449 
 1450 __initcall(init_mqueue_fs);
Cache object: 57e22a355cc54cef0226f7d2e509643a
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FreeBSD/Linux Kernel Cross Reference sys/ipc/mqueue.c

FreeBSD/Linux Kernel Cross Reference
sys/ipc/mqueue.c
